In recent years a large body of research evidence has accumulated supporting the concept that AIDS is an immunological disease induced by HIV-1 rather than simply being caused by loss of CD4+ T-lymphocytes as a result of chronic cytopathic viral infection. It is therefore important to develop interventions that target the chronic immune stimulation induced by HIV-1 as well as the virus itself, (Sommerfelt 2011, Recent Translational Research in HIV/AIDS Ed. Dr. Yi-Wei Tang. ISBN 979-953-307-189-2. pp 493-510).
Previous research shows that antibodies to the carboxyterminal C5 domain of HIV-1 gp120 has been associated with lower immune activation and slower disease progression (Loomis-Price et al. 1998 J. Inf. Dis. 178:1306-1316; Warren R Q et al. 1991 J. Clin. Immunol 11: 13-21; Lifson et al. 1991 J. Inf. Dis 163:959-965). Indeed, disease progression was shown to accelerate if humoral (i.e. antibody) responses to this domain were lost (Wong et al. 1993 J. Inf. Dis 168: 1523-1527). Furthermore long term nonprogressors (LTNP) which represent 5% of HIV-infected individuals have sustained humoral responses to the carboxyterminal C5 domain of HIV-1 gp120 and can live in the absence of antiretroviral therapy for many years despite having some degree of viral load (Liegler et al. 1998 J. Infec. Dis. 178: 669-79; Gougeon et al. 1996 J. Immunol. 156:3509-20; Muro-Cacho et al. 1995 J. Immunol. 154:5555-66; Easterbrook et al. 1999 J. Infect. 28:71-73).
The C5 domain of gp120 is 13 amino acids long (amino acid residues 499-511 of gp120, and has the reference sequence B.FR 83.HXB2—TKAKRRVVQREKR). Its conservation across multiple virus clades is shown in Table 1. The only regions that show any substantial variation are at positions 500 and 507 of the sequence which may contain predominantly amino acids K, R and E at position (500) or predominantly Q and E at position (507).
TABLE 1(C5-domain for different multiple clades)C5SEQUENCESResiduesVIRAL CLADES (%)497-511AA1A2BCDAPTKAKRR 3.1%//58.3% 0.7%/VVQREKR APTKAKRR21.9%12.8%//23.5%33.0%VVEREKR APTRAKRR 3.1%//12.4%/ 1.7%VVQREKR APTRAKRR15.6%27.7%33.3%/ 3.0%33.3%VVEREKR APTEAKRR////16.8% 3.3%VVEREKR 43.7%40.5%33.3%70.7%44.0%68.3%
The table provided is based on 1066 sequences downloaded from the Los Alamos HIV-database 3rd of May 2008.
The sequences grouped in the following viral clades:
A: 32 sequences, A1: 47 sequences, A2: 10 sequences, B: 453 sequences, C: 464 sequences, and D: 60 sequences.
This carboxyterminal constant region C5 of HIV-1 gp120 is immunodominant and highly conserved across multiple HIV subtypes. It is exposed on the 3D structure of native gp120, on virions and on cell surface expressed gp120. Indeed, the C5 domain resembles human leukocyte antigen (HLA) classes I and II molecules and has the ability to bind peptides and deletion of the C5 domain abrogates peptide binding (Cadogan et al. AIDS Research and Human Retorviruses (2008); Vol. 24: 845-855). In this way the C5 domain can mimic the activities of human HLA.
International Patent Applications WO2011/000962 and WO2012/092934 disclose methods for treating HIV infections by administering e.g. at least one immunogen which induces antibodies that stabilise association of the C5 domain of HIV gp120 with the transmembrane domain of gp41 and/or with the constant C2 domain of gp120, and certain peptides suitable for such use.
Naturally occurring HIV sequences in vaccine candidates are not capable of stimulating a stable immune response due to the viruses inherent ability to hide by changing the appearance of the epitopes presented on the cell surface of infected cells. The immune system is fooled to believe that a particular amino acid sequence is relevant when in fact the amino acids of importance is hidden.
A study of titers of antibodies against the gag p24 protein, has shown that slow progression towards development of AIDS is associated with high titers, while fast progression towards development of AIDS is associated with low titers. It is shown that persons with low p24 antibody titer develop significantly faster AIDS than persons with high p24 antibody titers (Zwart G., et al. Virology, 201, p. 285-93, June 1994), indicating that p24 can play a key role to control the development of AIDS.
New HIV p24 peptides are described in WO91/13360, wherein the peptides are used in a method of discriminating between a false and true diagnosed HIV-positive serum sample.
Johnson R. P., et al., The Journal of Immunology, Vol. 147, p. 1512-1521, No. 5, Sep. 1, 1991 describe an analysis of the fine specificity of gag-specific CTL-responses in three HIV-1 seropositive individuals, the gag-specific CTL-responses were found to be mediated by CD3+CD8+ lymphocytes which are HLA class I restricted.
EP-A-0 356 007 discloses antigenic determinants, in particular it relates to synthetic polypeptide sequences which are related to proteins present in the HIV-1 and which can be used as a basis for a potential vaccine against AIDS.
Rosenberg E. S. et al., Science, Vol. 278, 21 Nov. 1997, p. 1447-1450 describe that virus specific CD4+ T helper lymphocytes are critical to the maintenance of effective immunity in a number of chronic viral infections, but are characteristically undetectable in chronic human immunodeficiency virus-type 1 (HIV-1) infection. HIV-1-specific proliferative responses to p24 were inversely related to viral load. They conclude that the HIV-1-specific helper cells are likely to be important in immunotherapeutic interventions and vaccine development.
EP 0 230 222, EP 0 270 114, DE 37 11 016 and GB 2 188 639 all in the name of F. Hoffmann-La Roche & Co. Aktiengesellschaft concern recombinant expression and purification of an HTLVIII Gag/Env gene protein or fusionproteins. The proteins consisting of native sequences can be purified to homogeneity and used as a basis for diagnostic tests for detection of antibodies against viruses associated with AIDS. The gag/env protein may also be formulated for use as a vaccine for protection against AIDS through prophylactic immunization.
From a diagnostic and therapeutic point of view, the major problems with using p24 as part of an assay or therapy is associated with the high number of epitopes on p24 which stimulates production of a large number of antibodies with poor specificity, which through repeated boostering on potential mutated sequences can create autoantibodies (Autoantibodies to the alfa/beta T-cell receptors in HIV infection; dysregulation and mimicry. Lake D. F., et al., Proc. Natl. Acad. Sci. USA, (23): 10849-53, Nov. 8 1994). Further, it is reported that the p24 antibody titer does not reach the same high levels as for the envelope proteins (gp120 and gp41). Normally antibodies to p24 are developed in the very early phase of the infection, but the titer is fairly quickly stabilized after the initial infection period. Later the p24 titer is gradually decreasing while the opposite happens with gp160. These findings can also be seen in relation to recent reports stating that cytotoxic T-cell activity is antagonized by naturally occurring HIV-1 gag variants (Klenerman P., et al., Nature, 2:369 (6479), p. 355, 2 Jun. 1994). This can be one of the reasons why a rapid stabilization of the p24 titer is seen and why it later starts to decrease.
International Patent Application WO00/52040 discloses methods for treating HIV infections by administering e.g. HIV specific peptides based on conserved regions of HIV gag p24.
There is a need to provide improved treatments for the HIV infections and AIDS.